Two long-serving PR executives at Facebook have quit following the shock appointment of former UK Deputy Prime Minister Nick Clegg as their boss.

Caryn Marooney, 51, leader of Facebook's communications group, and Debbie Frost, vice president of global communications and public affairs, announced they were resigning after a combined 19 years at the social media giant.

Frost said she planned to leave Facebook by March after nearly 11 years on the team. Marooney put out word on Wednesday that she is resigning after eight years and said she is working with Mark Zuckerberg and Clegg to find a replacement.

Caryn Marooney, leader of Facebook's communications group, has quit after eight years on the job. Her resignation follows the shock appointment of former UK Deputy Prime Minister Nick Clegg as her boss

Debbie Frost, vice president of global communications and public affairs, announced she planned to leave Facebook by March after nearly 11 years on the team

She wrote on her Facebook page 'It's time to get back to my roots' but noted that 'she had 'more faith in Facebook than ever'.

Marooney explained that, with Nick Clegg now settled in his role, it felt like the right time to move on.

With scant experience of neither public relations nor American politics, former Liberal Democrat leader Nick Clegg's appointment turned heads on both sides of the Atlantic.

Facebook founder and CEO Mark Zukerberg pictured with former Liberal Democrat Nick Clegg after appointment, which turned heads on both sides of the Atlantic

He was accused of hypocrisy for accepting a lucrative job working for Facebook even though he previously described its ‘messianic Californian new-worldy-touchy feely culture’ as ‘a little grating’.

It turned out, Clegg got the job through a man with whom he has had long-time personal links. The former Lib Dem leader’s mentor on his way to becoming a Westminster politician was Richard Allan.

Caryn Marooney explained that, with Nick Clegg (pictured) now settled in his role, it felt like the right time to move on

Most helpfully, Allan stepped down as Lib Dem MP for Sheffield Hallam, offering the chance for Clegg to stand as his replacement. This Clegg duly did, and was elected an MP — with Allan as his campaign manager.

Allan acted as his campaign manager again in 2007 when Clegg successfully stood to be Lib Dem leader.